Chapter 2 Notes Psychological Research Methods and Statistics Psychology Chapter 2 Notes Psychological Research Methods and Statistics

What is Research? Psychologists must first decide how to approach the research issue. Then they conduct the research in one of a variety of ways to test a hypothesis, solve a problem, or confirm previous findings Pre-Research Decisions Begin by developing a hypothesis Look for evidence/conduct research Researchers select a sample – a relatively small group out of the total population under study Must be representative of the population Choose a purely random sample Use a stratified sample – subgroups in the population are represented proportionally

Methods o f Research Naturalistic Observation – observing behaviors with out intruding or disturbing those being observed Case studies are intensive studies of a person or group of people Long-term observations Diaries Tests Interviews Surveys involve interviews and/or questionnaires. Very practical way to gather data

Longitudinal Studies occur when a psychologist studies the same group of people at regular intervals over a period of years to determine whether their behavior and/or feelings have changed and if so, how. Cross-Sectional Studies are when psychologist organize people into groups on the basis of age The groups are randomly sampled with simultaneously with Surveys Tests Observations

Correlations and explanations Correlations describe how two sets of data relate to each other Experiments Hypothesis – educated guess Variables – conditions and behaviors that are subject to change Independent variable is changed or altered so the experimenters can observe its effects Dependent variable changes in relation to the independent variable Experimental group – those who are exposed to the independent variable Control group – those who are not exposed to the independent variable

Ethical Issues Ethics are the methods of conduct or standard for proper and responsible behavior Plan to minimize possible misleading results Maintain the dignity and welfare of the participants Obey all state, federal, and professional laws, regulations, and standards Reach agreements regarding the rights and responsibilities of the participants and the researchers Obtain signed, informed consent Deception is used only if no better alternative is available

Problems and solutions in research The investigation of psychological issues is a painstaking process. Psychologists must recognize and resolve errors while doing research Self-fulfilling Prophecy Self-fulfilling Prophecy involves having expectations about a behavior and then acting in some way, usually unknowingly to carry out that behavior Avoiding a Self-fulfilling Prophecy Double-blind experiment – neither the experimenter nor the participants know which participants are receiving the experimental stuff Single-blind experiment – the participants don’t know if they’ve received the stuff or the placebo, but the experimenter does.

The Milgram Experiment Stanley Milgram (1960s) Told people to act like they were receiving electric shocks to see how the person supposedly delivering the shocks would respond Most of those delivering the shocks continued to deliver them through the maximum capacity of electricity Conclusion was the people will hurt others when told to do so by an authority figure Placebo Effect Placebo effect happens when a person’s illness or physical state changes when they simply think they are receiving treatment

Statistical Evaluation Psychologists must collect and evaluate evidence to support their hypothesis. Descriptive Statistics Descriptive Statistics is the listing and summarizing of data in a practical, efficient way through graphs and averages Frequency distributions are common Frequency polygons are like line graphs that compare two sets of data Normal Curve (aka a bell curve) is where the curve is highest in the middle and tapers off towards both ends. It is symmetrical

Measures of Central Tendency Central tendency is a number that describes something about the “average” score Mode is the most frequent score Bimodal indicates there are two frequent scores/modes Mean is what most people think of as an average This is the balance point Measures of Variance Measures of variance provide an index of how spread out the scores of a distribution are Standard Deviation is a better measure of variance because it uses all the data points in its calculation.

Correlation Coefficients describe the direction and strength of the relationship between two sets of observations Positive correlation means as one variable increases so does the other Negative correlation means as one variable increases, the other decreases Scatterplots are graphs of scores on the two variables Inferential Statistics Inferential statistics allow researchers to determine whether the data they collect support their hypotheses, or whether their results are merely due to chance outcomes Probability - what is the probability that something will happen? Chance – could the results be due to chance?